1. Field of the Invention
The present invention relates to a longitudinally displaceable column of the type in which a longitudinal adjusting unit is supported on a base plate of a vertical support tube and, in particular, in which a rod of the adjusting unit receives an axial bearing that is interposed between the rod and the base plate to enable the rod to rotate relative to the base plate.
2. The Prior Art
DE 41 29 089 A1 discloses a longitudinally displaceable column for height adjustment of chairs, tables or the like, having a vertical tube with a longitudinal pneumatic or hydropneumatic adjusting unit arranged therein concentric to a common central longitudinal axis. A housing of the adjusting unit is supported radially in the tube and is guided for displacement in the direction of the axis. A piston rod is affixed on a base plate of the tube against movement in the direction of the axis and is supported for rotation with respect to the base plate by means of an axial rolling bearing preassembled into a unit. U.S. Pat. No. 5,120,011 also describes and shows a longitudinally displaceable column.
The purpose of a preassembled bearing unit can be seen in that assembly of the longitudinal adjusting unit is substantially facilitated. Rolling members cannot fall out of the bearing. Despite this, the bearing unit has the disadvantage of relatively high costs, which it is the object of the invention to minimize.